CODESAMPLE

Facade - Dart

Facade Dart

The Facade pattern provides a simplified interface to a complex subsystem. It defines a high-level interface that hides the complexities of the lower-level system. This makes the subsystem easier to use and understand for clients.

The Dart code demonstrates a media player facade, simplifying interactions with components like file system, audio decoder, and video renderer. The MediaPlayer class offers methods like play() and stop() which internally orchestrate the complex operations of these subsystems. This approach encapsulates the complexity and presents a clean, easy-to-use API. Dart’s class-based structure naturally lends itself to the Facade pattern, allowing for clear encapsulation and a well-defined interface.

// Subsystem 1: File System
class FileSystem {
  String readFile(String filePath) {
    print('Reading file from: $filePath');
    return 'File content from $filePath';
  }
}

// Subsystem 2: Audio Decoder
class AudioDecoder {
  String decode(String data) {
    print('Decoding audio data');
    return 'Decoded audio: $data';
  }
}

// Subsystem 3: Video Renderer
class VideoRenderer {
  void renderVideo(String data) {
    print('Rendering video: $data');
  }
}

// Facade: MediaPlayer
class MediaPlayer {
  final FileSystem _fileSystem = FileSystem();
  final AudioDecoder _audioDecoder = AudioDecoder();
  final VideoRenderer _videoRenderer = VideoRenderer();

  void play(String filePath) {
    print('Playing media from: $filePath');
    String fileContent = _fileSystem.readFile(filePath);
    String decodedAudio = _audioDecoder.decode(fileContent);
    _videoRenderer.renderVideo(decodedAudio);
    print('Media playing...');
  }

  void stop() {
    print('Stopping media...');
    // Add stop logic for subsystems if needed
  }
}

// Client code
void main() {
  final mediaPlayer = MediaPlayer();
  mediaPlayer.play('path/to/media.file');
  mediaPlayer.stop();
}